Over recent years, an image forming system has not only simply carried out image formation, but also increased office work efficiency by providing a post-processing apparatus to carry out various kinds of post-processings. Such post-processings include, for example, punching processing, stapling processing, sheet-inserting processing to insert a cover sheet or an insert sheet, folding processing such as center-holding or tri-folding, and bookbinding processing.
As one of the bookbinding processings, there is ring-bookbinding processing. In this ring bookbinding processing, to a plurality of holes punched in a sheet bundle, a ring binder as shown in, for example, Unexamined Japanese Patent Application Publication No. 2007-30319 is attached, and then the rings are closed for ring binding of the sheet bundle to produce a booklet.
With regard to this ring bookbinding, various types of proposals have been made. For example, Unexamined Japanese Patent Application Publication No. 2009-256070 discloses a technology in which in an image forming system provided with a sheet inserting apparatus and a ring bookbinding apparatus, on ring binding processing, a judgment is made whether or not punch holes having been previously punched in a sheet are present; in the case of the presence of punch holes, the ring bookbinding apparatus is not allowed to punch punch holes, and in contrast, in the case of the absence of such punch holes, the punching function of the ring bookbinding apparatus punches punch holes.
Unexamined Japanese Patent Application Publication No. 2010-44429 discloses an image forming system in which in an image forming apparatus provided with a sheet inserting apparatus and a post-processing apparatus, on post-processing using an insert sheet, a non-image sheet standard mode to assign the inserting position of a sheet (image sheet) having an image formed on the basis of an insert sheet (non-image sheet) and an image sheet standard mode to assign the inserting position of a non-image sheet on the basis of a normal image sheet can be selectively used. This system intends to simplify the operation by instructing sheet insertion using the non-image sheet standard mode, when a large number of non-image sheets are handled
Further, Japanese Translation of PCT International Application Publication No. 2008-505787 discloses another example of a ring binder (binding tool) used for ring bookbinding. The ring binder disclosed in Japanese Translation of PCT International Application Publication No. 2008-505787 has such a structure that a spine portion and a plurality of finger portions extending from the spine portion are provided and the finger portions are inserted into the punch holes of a sheet bundle and rolled for connection to the spine portion to form a rolled ring binder.
Japanese Translation of PCT International Application Publication No. 2008-505787 discloses that, between the rear cover (last sheet) and the last sheet of the main body sheets, a spine portion is arranged and then the spine portion is covered to provide an attractive appearance for a bound book. Since the finger portions are rolled with a length based on the thickness of the sheet bundle, the length is formed longer with some allowance. Therefore, in a common binding method, on the rear cover side, the spine portion and the long finger portions appear, resulting in disfigurement. Japanese Translation of PCT International Application Publication No. 2008-505787 intends to cover such a spine portion and finger portions by the rear cover. Further, WO/2007/021578 discloses an apparatus constitution to carry out ring bookbinding employing the ring binder of Japanese Translation of PCT International Application Publication No. 2008-505787.
To arrange a spine portion between the rear cover and the last page of a sheet bundle as described in Japanese Translation of PCT International Application Publication No. 2008-505787 and WO/2007/021578, as the order of feeding sheets to a ring bookbinding apparatus, initially, the last sheet serving as the rear cover is fed and then main body sheets with images formed are successively fed to carry out ring bookbinding, and then the rear cover of the finished booklet is turned over to be positioned on the rear side of the main body sheets.
Further, Unexamined Japanese Patent Application Publication No. 2009-119712 discloses a ring binder similar to that of Japanese Translation of PCT International Application Publication No. 2008-505787.
The present invention relates to the control of image formation in the case where ring bookbinding disclosed in above Japanese Translation of PCT International Application Publication No. 2008-505787 and WO/2007/021578 is carried out in which a spine portion is arranged between the final sheet (rear cover) and the last sheet of the main body sheets.
In general, an original document is set on the automatic document reading apparatus and then an original image is read to carry out image formation. However, the presence or absence of an image in the last original document is unclear until termination of original document reading. Therefore, to arrange a spine portion between the rear cover and the last sheet of the main body sheets as described in Japanese Translation of PCT International Application Publication No. 2008-505787 and WO/2007/021578, after the complete termination of original document reading, a judgment whether or not an image to be printed is present in the last original document is made, and thereafter image formation is initiated.
To further detail this respect, an example of a booklet bk produced using a ring binder provided with a spine portion is shown in FIGS. 8a and 8b. FIG. 8a is a perspective view showing the state of a booklet bk immediately after produced. In this state, exposure of the spine portion on the surface results in poor appearance. To circumvent this problem, it is possible that the user turns over a sheet at the bottom via one-sheet flipping to create the completed state of FIG. 8b. The sheet S flipped in this case is used as the rear cover.
FIGS. 9a, 9b and 9c are schematic views illustrating the printing order in an image forming system to produce a booklet of the state as shown in FIG. 8a. FIG. 9a is a view showing the order of original document reading. FIG. 9b is a view showing the order of printing image data obtained via reading. FIG. 9c is a view showing the state when sheets were stacked in a stacking section in the order of printing and thereby a sheet bundle was produced to carry out bookbinding for the thus-produced sheet bundle using a ring binder rb. Further, the arrow shown in FIG. 9a shows the position when the spine portion rb1 of the ring binder rb is inserted.
To obtain a booklet bk as shown in FIGS. 8a and 8b, as shown in FIG. 9c, the last, nth sheet is placed as the bottom layer, and thereon, the (n−1)th sheet is stacked in the order from the first sheet to produce a sheet bundle. Then, a ring binder rb is attached to the thus-produced sheet bundle to produce a booklet bk as shown in FIG. 8a. Namely, as the printing order, as shown in FIG. 9b, initially, image data of page n is printed on the nth sheet and then image data is printed on sheets starting from the first sheet to the (n−1)th sheet in this sequential order.
On the other hand, as shown in FIG. 9a, original document reading is carried out in the order from the first page (first sheet) to the nth page (nth sheet), but the printing order is as follows: the nth sheet, the first sheet, the second sheet, . . . , and the (n−1)th sheet.
As shown in FIG. 9a, original document reading of the last, nth sheet is terminated last. Therefore, without termination of entire original document reading, image formation cannot be initiated, resulting in low productivity.
In view of these circumstances, an object of the present invention is to provide an image forming system capable of initiating image formation before terminating the acquisition of the entire image data and of reducing the entire processing time of image formation.